Manufacture of bricks for furnaces.



- hundred.

' UNITED STATES Patented August 4, 1903.

PATENT OFFICE.

JAMES EUGENE KIRKPATRICK, OF TAUNTON, ENGLAND.

"$315GIFICA'JJION forming part of Letters Patent No. 735,528, datedAugust 4, 1903.

Application filed May 16,1903. $erial No. 157,477. (No specimens) To awhom it may concern:

Be it known that I, J AMES EUGENE KIRK- PATRICK, a subject of the Kingof Great Britain, residing at Taunton, in the county of Somerset,England, have invented certain new and useful Improvements in theMannfacture of Bricks and Compositions Capable of Withstanding Very HighTemperatures and for Use in Steel and other Furnaces, of which thefollowing is a full, clear, and exact description.

The invention has for its object the manufacture of basic magnesitebricks and magnesite compositions for use in steel and other furnaces.

I employ'crude magnesite-such, for example, as that found in Salem andother parts of India, the composition of which is approximately asfollows: magnesium carbonate, 90.56; magnesium oxid, 7. 64; siliconoxid, 0.97; aluminium oxid, 0.32; iron oxid, 0.19; loss and watercombined, 0.32; total, one

The reason for using this description of magnesite is the very smallproportion of silicon,'iron, and aluminium contained therein. brick orcomposition, also the small proportion of lime, is an advantage, as thebricks on cooling from high temperatures have not the tendency to splitin the manner those do which are made from magnesite containing largequantities of lime.

This .invention consists of the hereinafterdescribed method of treatingmagnesite of the description before mentioned to utilize it in themanufacture of bricks and other compositions or formations for use inbasicsteel and other furnaces.

My invention only deals with magnesite of the purity described. The lesspure magnesite existing in many countries containing large quantities ofsilicon, alumina, iron, and lime can without any special preparation ortreatment be made into bricks, &c., and kilnburnt; but they are greatlyinferior in quality to those made from magnesite of the great purityherein first referred to.

Now according, to this invention crude magnesite, such as herein firstdescribed, is first dead burnt in either an electric, rotary, or anyother furnace or kiln in which a temperature ranging from 1,000 to 2,000cen Hence the greater basicity of the.

tigrade may be obtained to free it from carbon dioxid and any othervolatile or organic impurities it may contain. If desired, this part ofthe process maybe carried to the fusion-point of the substance-that isto say, the effect of fusing the substance does not inju re itsproperties for the purpose for which it is to be used; but it is notabsolutely necessary to continue the dead-burning until fusion takesplace. This dead-burnt substance is then crushed either to a fine powderor to a powder of a coarser nature suitable for the various purposes forwhich the final product is to be used. In the manufacture of bricks ofthe ordinary dimensions the quantity of the fine powder to be mixed withthe coarse is not more than from one to two per cent.; but in themanufacture of large slabs or bricks the quantity will vary inaccordance with the size of the slab or brick; but in any case thelargest proportion possible of the coarse is used, as this insuresgreater refractory properties and greater strength in the final product.This crushed dead-burnt magnesite is now exposed to the atmosphere in asuitable shed or room fora period of at least forty-eight hours. Thispart of the process may be continued for a longer period; but extremecare must be taken to safeguard against the absorption of too great aquantity of carbon dioxid. If from overexposure to the atmosphere a verylarge proportion of this gas is absorbed, the bricks will show cracksand other defects after kilning. During such exposure the crusheddead-burnt magnesite is to be frequently turned over by hand ormechanical means, so as to expose all portions equally during suchexposure. This is most essential to the working of the process, for ifthis turning over ofthe material is not carried out and the top layer istaken by itself and made into bricks on kilning such bricks will fall topieces in an almost pulverulent state. Hence by neglect of thisimportant matter the whole kiln of brick may be rendered useless fromdefects in shape, &c. The crushed dead-burnt magnesite after suchexposure is intimately mixed with a small proportion-say from one to tenper cent. of its weight-of sodium pyroborate, commonly known as sodiumbiborate or borax, or the native borax of India, known as tinkal,tincal, or tinstone, may be used after such purification as may benecessary in order not to materially increase the amountofiron,silicon,aluminiuin, orcalcium contained in the original magnesite. Theamount of borax or tinstone used may vary according to the purpose forwhich the brick, &c., is intended to be used. Water is now added to thismixture of dead-burnt magnesite and sodium pyroborate, and it is ofextreme importance that the quantity of water used should only besuflicient to moisten the mixture, so that it may be convenientlyhandled' in a mass. If a larger quantity than necessary is used, thebrick, &c will in the process of drying give off the excess of Waterwith such rapidity as to render the brick, 8.70., unsound from cracksand other defects in its internal parts. This mass may then be molded insitu, or it may be molded to the necessary shape by the usual'methodsemployed in molding ordinary clay. The mold ed substance is nowsubjected to a drying process. The temperature of the dryingroom orstove should not greatly exceed 100 Fahrenheit. I find that drying-roomssuch as are in use in the manufacture of ordinary clay bricks, in whichthe exhaust-steam from the boilers employed in such works is used forthe purpose, are very suitable for the purpose of drying these bricks.The time al lowed for drying ordinary-sized bricks is generally fromtwelve to twenty-four hours. As soon as this part of the process iscomplete the bricks, &c., are immediately subjected to hydraulic orother similar pressure and may then be burned either in situ or in anordinary well-constructed kiln, an electric furnace, or by any othermethod in which a sufiicientlyhigh temperature can be obtained.

I am well aware that it has previously been proposed to manufacturebricks from native magnesite of the purity to which this process isapplicable, but not in the manner herein prescribed, and the difficultyto contend with has been that the small proportion of easilyfusiblematerials contained in this native mineral is not sufiicient to hold theparticles together when manipulated by ordinary methods and that theaddition of silicon, silicon fluorid, alumina, iron, &c., destroyed theobject to be attainednainely, the preservation of the great basicity ofthe final product for the important purpose it is intended to be usedt'.e., primarily the lining of basic-steel furnaces-Whereas by manipulationof the substance in the manner herein described, with the addition of asuitable quantity of that easily-fusible substance borax, thisditficulty is overcome, and the finished product has still the samebasicity as the original native magnesite.

In the process of burning this composition the sodium pyroborate orborax not only acts as an easily-fusible mineral salt, simply holdingthe finely-granulated atoms or granules of magnesite together, butchemical combination takes place. This may be demonstrated by subjectinga portion of such brick to the temperature at which sodium pyroborate isfusible and gradually raising the same to the temperature at which themagnesite itself becomes fusible, and on subsequent cooling anddecomposition with acids the reaction given by the metal boron isevidenced on the application of the usual chemical tests.

Having now particularly described and ascertained the nature of mysaidinvention and in what manner the same is to be performed, I declare thatwhat I claim isl. The manufacture of bricks and compositions capable ofwithstanding very high temperatures from crude magnesite of a highdegree of purity such as that found in many parts of Southern India bythe following process, viz: first, dead-burning the magnesite to free itfrom carbon dioxid and any other volatile or organic impurities it maycontain; second, crushing the dead-burnt magnesite to powder; third,exposing the crushed dead-burnt magnesite to the atmosphere andfrequentlytnrning itover; fourth, mixing the crushed dead-burntmagnesite after exposure to the air with asmall proportion of its weightof borax; fifth, adding only sufficient water to the material to enableit to be conveniently handled in a mass; sixth, molding the mass to therequired shape; seventh, drying the molded mass; and, eighth, burningthe dried molded mass at a high temperature; substantially as herein setforth.

2. The manufacture of bricks and compositions capable of withstandingvery high temperatures from crude magnesite of a high degree of purity,such as that found in many parts of Southern India, by the followingprocess, viz: first, dead-burning the magnesite to free it fromcarbon-dioxid and any other volatile or organic impurities it maycontain; second, crushing the dead-burnt magnesite topowder; third,exposing the crushed dead-burnt magnesite to the atmosphere andfrequently turning it over; fourth, mixing the crushed dead -burntmagnesite, after exposure to the air, with a small proportion of itsweight of borax; fifth, adding only sufficient water to the material toenable it to be conveniently handled in a mass; sixth, molding the massto the required shape; seventh, drying the molded blocks; eighth,subjecting the molded blocks to great pressure; and, ninth, burning thepressed molded blocks ata high temperature; substantially as herein setforth.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

JAMES EUGENE KIRKPATRICK.

lVitnesses:

PEARD CLARKE, JAMES SHAIRCROSS.

ICC

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